Fiorentina's fans and their flares were not the only ones who would have turned the Tuscan night air violet last night. The Liverpool manager, Rafa Benitez, watched the defensive problems which have been there all along throughout a resurgent past month for his side laid bare by a 19-year-old.

It means that any thoughts that Group E will be some kind of a procession for Liverpool can be firmly laid to rest.

Fiorentina were another of those sides who bowed down before the reputation of Liverpool and their manager in Europe. "Welcome Reds, your story for us is a legend," read the banner which was paraded around the ground at the end, part of a twinning arrangement between the two sets fans. Benitez had brushed off local compliments with a smile and a joke, as surely intended for the Liverpool kit man. But their reputation is evolving from one of defensive tightness to generosity as they try to introduce more adventure to their game and the midfield were bearing some unexpected gifts for the Italians, too.

Benitez's gamble in deploying Fabio Aurelio rather than Steven Gerrard in the deep lying midfield role was one which backfired badly and the beneficiary was Stevan "Jo-Jo" Jovetic, a teenager with curls whom they know in these parts as the "Montenegrin Messi" and who had not even scored a goal in Europe until the strike in a qualifier against Sporting Lisbon which sent Fiorentina through. "We knew about him. We were watching some of his games," Benitez said later. Too late now. His two goals in nine minutes came as Liverpool's defence was torn to shreds.

When asked on Monday evening which of Jovetic or Adrian Mutu was a worry with Alberto Gilardino, the Italians' main goalscorer missing, Martin Skrtel said: "I fear no-one." He was on his haunches at the end, staring at the turf and preparing to eat his words. Benitez blamed a vague and general lack of purpose, though his DVD analysis will reveal something more serious – specific, technical faults.

By way of contrast, he may look again at Alessandro Gamberini, launching himself into an immaculately timed 69th-minute tackle on Fernando Torres, curtailing the Spaniard;s sole opportunity to run straight into the Italians' penalty area. Liverpool never threatened after that and the group has a different complexion now; Lyons' 4-0 win in Debrecen putting the lame win over the Hungarians at Anfield into some kind of context. Liverpool meet the French side next.

Benitez says he needs balance between attack and defence, and though this defeat is a minor setback, bearing no comparison with the one to Besiktas in Istanbul two autumns ago, which set Liverpool on the brink of elimination, the wait for Alberto Aquilani to secure the defence cannot come soon enough. Benitez also expects Javier Mascherano, the night's significant absentee through a hamstring strain, back to face Chelsea on Sunday.

Skrtel certainly seems to need him. Jamie Carragher is the player whom Benitez has taken aside for a discussion on performance at Melwood but it was Skrtel who looked anxious from the start. He needed a desperate early block as he retreated in pursuit of Jovetic, already Montenegro's captain, who was sent through by Riccardo Montolivo. Skrtel was also powerless when Cristiano Zanetti dispossessed the feckless Lucas Leiva and placed the fine measured pass which Jovetic latched onto and rolled, right footed to the right of the advancing Jose Reina. The retreating Adrian Mutu was offside but Liverpool could have no quarrel as he was not interfering with play

Dire, then disastrous. Jovetivic's second goal exposed pretty much every quarter of Liverpool's defence - Emiliano Insua, who allowed Marco Marchionni the space to advance down Liverpool's right and cross; Skrtel, who could only head out to Juan Vargas; Glen Johnson whose positional play let Vargas collect the ball and shoot from the left of the Liverpool box; Skrtel who had by then allowed Jovetic to evade him to score.

Benitez has put this down simply to the risk of Liverpool's more attacking brand of football but Fiorentina's seven first-half efforts compared with their one – a tame shot from Gerrard. He and Torres had looked utterly isolated.

They found some spirit immediately after the interval. Yossi Benayoun immediately cut in from the right to force a low save from Sebastien Frey at his near post and from the resulting Aurelio corner, Leiva – allowed a free run into the area – could only head over. Dirk Kuyt fired another hard low shot which Frey saved.

However, this city was being painted violet, Fiorentina proud that none of the five English sides who have travelled here in European competition have won. The raucous Curva Fiesole had sung and bounced the evening away and, before the game, had echoed to the sounds of red and white balloons being burst. Liverpool's reputation for steadfastness has a hole in it, too.